Memorial day plannin
Ko requires reservations and doesn't take walk-ins. Noodle Bar only takes them for the fried chicken meal. Ssam Bar only takes them for the bo ssam meal. Milk Bar is take-out. Ma Peche does not take reservations.
Momofuku Ko only accepts reservations via the web site. The calendar always shows seven days for dinner and 14 days for lunch (this includes the current day). New reservations only open up at 10am and are typically gone in seconds. Lunch is easier than dinner because it is more expensive; however, it is only served on Fridays, Saturdays, and Sundays. Ko is almost always fully committed.
At Momofuku Noodle Bar, they only take reservations for the fried chicken meal for 4-8 people. Reservations are only taken 27 days in advance (i.e., 4 weeks minus one day) and are fairly difficult to obtain because this dinner is currently very buzzy. They do, however, serve it at dinner and lunch.
At Momofuku Ssam Bar, they only take reservations for those that order the bo ssam dinner for 6-10 people. Reservations are only taken 27 days in advance (i.e., 4 weeks minus one day) and are fairly easy to obtain if you plan ahead because this meal has been offered for a while now.
Even though you plan to dine in NYC over Memorial Day, I would expect demand for Ko reservations and Noodle Bar fried chicken meals to remain high.